The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution

Rajić, Ljiljana; Fallahpour, Noushin; Podlaha, E. J.; Alshawabkeh, Akram N.

doi:10.1016/j.chemosphere.2015.12.095

Cited by 45 publications

(21 citation statements)

References 68 publications

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“…Fe electrodes were immersed in 1M HCl to remove any foreign metals and surface oxide layers. The palladization procedures for Fe and Cu foam were performed under the conditions given in Rajic et al, 2016. The Pd content at Fe and Cu was 0.5 mg cm −2 of geometric electrode surface area.…”

Section: Methodsmentioning

confidence: 99%

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Electrochemically-induced Reduction of Nitrate in Aqueous Solution

Rajic¹,

Berroa²,

Gregor³

et al. 2017

International Journal of Electrochemical Science

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In this study, we evaluated the removal of nitrate from synthetic groundwater by a cathode followed by an anode electrode sequence in the electrochemical flow-through reactor. We also tested the feasibility of the used electrode sequence to minimize the production of ammonia during the nitrate reduction. The performance of monometallic Fe, Cu, Ni and carbon foam cathodes was tested under different current intensities, flow rates/regimes and the presence of Pd and Ag catalyst coating. With the use of monometallic Fe and an increase in current intensity from 60 mA to 120 mA, the nitrate removal rate increased from 7.6% to 25.0%, but values above 120 mA caused a decrease in removal due to excessive gas formation at the electrodes. Among tested materials, monometallic Fe foam cathode showed the highest nitrates removal rate and increased significantly in the presence of Pd catalyst: from 25.0% to 39.8%. Further, the circulation under 3 mL min−1 elevated the nitrate removal by 33% and the final nitrate concentration fell below the maximum contaminant level of 10 mg L−1 nitrate–nitrogen (NO3-N). During the treatment, the yield of ammonia production after the cathode was 92±4% while after the anode (Ti/IrO2/Ta2O5), the amount of ammonia significantly declined to 50%. The results proved that flow-through, undivided electrochemical systems can be used to remove nitrate from groundwater with the possibility of simultaneously controlling the generation of ammonia.

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Section: Methodsmentioning

confidence: 99%

“…This approach has been developed to use as in situ groundwater technology to remove trichloroethylene (TCE) from groundwater, and we found that nitrates presence adversely influences TCE removal. We found that nitrate presence adversely affects TCE hydrodechlorination by using a cathode followed by an anode sequence (Rajic et al 2016). …”

Section: Introductionmentioning

confidence: 99%

Electrochemically-induced Reduction of Nitrate in Aqueous Solution

Rajic¹,

Berroa²,

Gregor³

et al. 2017

International Journal of Electrochemical Science

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“…It has been reported that TCE and nitrate are removed through the electrode-based electrochemical processes at cathode surface, therefore their removal efficiencies are subject to the factors that are related to the mass transfer effect of contaminants on electrode/liquid interface, such as hydraulic residence time and surface area of the electrode [6]. According to previous studies, a flow-through cell with the cathode placed in front of the anode with respect to the flow direction, nitrate presence adversely affects TCE hydrodechlorination by using a cathode followed by an anode sequence [9]. Further study by Lu et al (2010) on TCE degradation in the presence of nitrate indicated that higher nitrate concentration directed to an increased amount of precipitates that acted as a physical barrier and slowed degradation rate of TCE.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Fallahpour

Mao

Rajić

et al. 2017

Journal of Environmental Chemical Engineering

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A small-scale flow-through limestone column was used to evaluate the effect of common coexisting organic and inorganic compounds on the electrochemical dechlorination of trichloroethylene (TCE) in karst media. Iron anode was used to produce ferrous ions and promote reducing conditions in the column. The reduction of TCE under 90 mA current, 1 mL min−1 flow rate, and 1 mg L−1 initial TCE concentration, was inhibited in the presence of humic acids due to competition for direct electron transfer and/or reaction with atomic hydrogen produced at the cathode surface by water electrolysis. Similarly, presence of 10 mg L−1 chromate decreased TCE reduction rate to 53%. The hexavalent chromium was completely reduced to trivalent chromium due to the ferrous species produced from iron anode. Presence of 5 mg L−1 selenate decreased the removal of TCE by 10%. Chromium and selenate complexation with dissolved iron results in formation of aggregates, which cover the electrodes surface and reduce TCE dechlorination rate. Presence of 40 mg L−1 nitrates caused reductive transformation of TCE up to 80%. Therefore, TCE removal is influenced by the presence of other contaminants that are present as a mixture in groundwater in the following order: humic acid, chromate, selenate, and nitrate.

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“…Due to the costly materials used and the intriguing catalytic properties of nanomaterials, electrocatalysis on shape‐controlled noble metal nanoparticles has received an increasing attention for the reductive dehalogenation over the past several years, e. g., For instance, the Pd NPs loaded on different supporting materials exhibit remarkable electrocatalytic hydro‐dechlorination performances for the various aryl chlorides including chlorophenols and chlorophenoxyacetic acids, where the exposed (111) facets was considered to be highly active for triggering the reductive dechlorination reactions …”

Section: Critical Factors For Controlling the Electroreductive Dehalomentioning

confidence: 99%

Insights into Electroreductive Dehalogenation Mechanisms of Chlorinated Environmental Pollutants

et al. 2020

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The electroreductive cleavage of carbon‐chloro bonds has attracted increasing attention from both environmental and mechanistic points of view over the past decades, taking into consideration a large variety of chlorinated organic compounds. Important discoveries have been made on the underlying electron/hydrogen transfer mechanisms and the enhancement of dechlorination performance for electrocatalysis purposes over the last years. However, there is still missing a combined knowledge from individual researches to specially elucidate the electroreductive dehalogenation mechanisms of organic chlorides. Herein, we summarize the diverse electrochemical strategies applied to reductive dehalogenation of chlorinated environmental pollutants, including direct electrochemical reduction, electrocatalytic hydro‐dechlorination and electrochemically mediated reduction methods, and, especially, highlight the differences in reductive dehalogenation mechanisms. Specifically, direct electron transfer is the most common dechlorination mechanism involved in the direct electrochemical reduction of organic chlorides, in which the electron transfer to C−Cl bonds can be classified as concerted or stepwise dissociative electron transfer mechanism. Indirect atomic hydrogen reduction is the primary dechlorination mechanism in the electrocatalytic hydro‐dechlorination process, which often competes with the direct electrochemical reduction route. Electrochemically mediated reduction, as another indirect route, uses a redox‐active mediator to indirectly transfer electrons from cathode to organic chlorides, resulting in reductive dehalogenation reaction. Moreover, the effects of critical factors on the dehalogenation reactivity and mechanisms are also discussed to better demonstrate the electroreductive dehalogenation of organic chlorides. Lastly, this contribution highlights recent relevant advances in electroreductive dehalogenation issues, as well as the challenges and potentials of this process.

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The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution

Cited by 45 publications

References 68 publications

Electrochemically-induced Reduction of Nitrate in Aqueous Solution

Electrochemically-induced Reduction of Nitrate in Aqueous Solution

Electrochemical dechlorination of trichloroethylene in the presence of natural organic matter, metal ions and nitrates in a simulated karst media

Insights into Electroreductive Dehalogenation Mechanisms of Chlorinated Environmental Pollutants

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